Thread: keep having trouble with this..

Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified axis.

y=20x–5x^2
y=0


about the y-axis.


How I started the problem was I solved the first equation and got [0,4]. And then I used these numbers and plugged it into the shell method.
The equation that I used for the shell method was the first one equation that I listed.


My answer was 853.33pi.


But, it's incorrect. Can someone show me how to setup and solve the problem?

Originally Posted by abilitiesz

Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified axis.

y=20x–5x^2
y=0


about the y-axis.


How I started the problem was I solved the first equation and got [0,4]. And then I used these numbers and plugged it into the shell method.
The equation that I used for the shell method was the first one equation that I listed.


My answer was 853.33pi.


But, it's incorrect. Can someone show me how to setup and solve the problem?

cylindrical shells ...